Hello everyone... and thanks in advance.

I'm cross posting this, so if it reads kinda "weird" that is why.

I'm trying to do a wiring harness from scratch on a race car.
Its a 1967S 2.0/6 motor....

first question: Would this be an internal or external voltage regulator on the alternator? (I'm guessing its an external, so I probably need to wire a regulator in somewhere)

second question: I'm replacing the tiny alternator warning light with a LARGE warning light.... I've seen this on other cars but they usually had a full wiring loom intact.

a)Do I need to pay attention to the wattage of the warning light bulb to get the circuit to excite?

b)should I wire a resistor in line to meet this need of a particular wattage and then wire my warning light seperate?

c) if b is true, then how would I wire the light seperate?

d) help...?

that should about cover all my questions for the next 24 hours or so... Most of the circuits (ie: fuel pump, switched ignition power, etc.) have made simple sense... but I'm struggling a bit with the alternator so thanks a ton fellas!!!!

brant

On mine I used the parking brake light as an big oil warning light. It was a simple plug and play.

Why are you worried about the alternator on a track car? You can run an entire weekend without it. Ask me how I know.

hell, ditch the alternator and free up some power!

The alternator light is very specific, don't go mucking about with it.

If the alternator light comes on, then you may have lost the belt and your cooling system. That is why you may want a big light.

That should be an external regulator.

In my experience any incandecent bulb you find to use as a warning light should be OK as an exciter.

Ooops...

not enough details huh..
Its a -6
If I throw the fan belt, the cooling fan stops working and I cook the heads.

so I want some kind of alternator warning to tell me when the belt is off.

I have no factory wiring left what so ever. No regulator, no dash, no original guages to tap into... I'm making up a full harness from scratch so that it will be lighter than stock.

Is there a way to forget about the alternator circut and wire in some other type of switch to alert me to when the belt is off?

I've got the warning lights I want already, but am trying to figure how to wire them

brant

oops...

what james said (we must have been posting at the same time)

external.. should be easy enough. Thanks James.

now.. hmmm.. regarding the warning light.
kinda feels like 2 options:
1) replicate the factory wiring for a warning light and make sure my new bulb is close enough to the same wattage
2) put a resistor in place of the factory bulb (this way I know its correct and the charging system will work). Then come up with a whole new manner of triggering my warning light...

is option 2 possible?

brant

1) 2 watt bulb.

2) Try this relay that has close enough coil resistance to use in place of the exciter bulb and use the relay contacts to switch a warning light up to 30 amps.

You could also make a transistor circuit, but you probably understand the relay better.

Another possibility, you could wire a superbright LED with current-limiting resistor (typically about 470 ohms) across the existing alternator light, or replace the bulb with a power resistor around 10-20 ohms and suitable wattage. Wire the LED up somewhere easy to see, you can use small gauge wire. It will only light when the alternator fails and there's enough voltage across the stock indicator lamp (or the substitute resistor). There are also some inexpensive alarms (Sonalert, etc.) to give an audible indicator.

Here's a link to request free samples of the Sonalert parts http://www.mallory-sonalert.com/request_samples.htm

Follow-up: Check out the LSC series, small audible alarm with built-in ultrabright LED flashing indicator. That should get your attention.

Later 911's use the switch pictured below to detect a broken belt. Wire it up to lights, buzzer or what ever. Using this you can tell the difference between an electrical problem or a broken belt. It would really suck to pit-in just because the voltage regulator crapped out.

James,

thanks a ton.. that looks like one good solution.

ejm, I know very little about the late cars... but I'm assuming that the pictured switch only works in conjunction with the idler on the late cars.

I won't be putting an idler into my setup... so do you know how the switch works?

brant

The roller and switch is one part, it mounts on a little bracket. The roller is on a spring loaded arm, when the belt breaks the arm swings over and activates the switch. Very easy to adapt to an earlier engine. Last I checked a few years ago the part was around $70

EJM,

ok... so if I'm understanding (forgive me for not having any coffee yet)...

the roller is not a tensioner, just a roller.
and you could retro-fit it onto an early motor and keep the stock fanbelt and all in place.

hmmm...

A tad bit more weight, but simple too..
which years of motors run this set up (to steal parts from)?

tia
brant

Mallory Son-a-lert is a great product, durable and reliable.

Exactly...was used on early to mid '90 911's...shown in PET illustration 105-00 with the cooling fan...